The present invention relates to techniques for analyzing an image showing a graphical representation.
Bunke, H., "Attributed Programmed Graph Grammars and Their Application to Schematic Diagram Interpretation," IEEE Transactions on Pattern Analysis and Machine Intelligence, Vol. PAMI-4, No. 6, November 1982, pp. 574-582, describes techniques that apply attributed programmed graph grammars to the interpretation of circuit diagrams and flowcharts. Section II on pages 574-577 explains attributed programmed graph grammars. Section III on pages 577-582 describes application to line drawing interpretation, including circuit diagrams and flowcharts. A circuit diagram given in terms of lines can be interpreted, and an output graph representing an interpretation result can be obtained. FIG. 10 shows an overview of a system for obtaining an output graph from an input image. An input graph obtained from an input image is transformed into an output graph by applying productions according to a control diagram. Page 580 describes error correction, and FIG. 20 illustrates a distorted version of a circuit diagram with errors that can be corrected. Flowchart interpretation is illustrated in FIGS. 18 and 19, described on page 581.
The Ricoh Imagio MF530 Series General Catalog, Ricoh K.K., 1992, describes AI copying functions at pages 23 and 24. Page 23 mentions that hand-drawn numerals are converted "as is" into graphs and that hand-drawn lines are converted into straight lines. Page 23 shows how different types of graphs can be created by writing numerals by hand on a form. Page 24 shows how hand-drawn charts, including a flow chart and two others that appear to have nodes and links, can be cleanly traced and thus made easier to see.